I don’t get into Windows vulnerability issues much here. I find it boring reading, the severity of these issues is often overblown (like everything else), and I used to get paid to protect systems from this stuff. If you like to keep up with such things I recommend BleepingComputer.
Anyway, below are the latest vulnerabilities. The fixes involve you not being able to print (at least remotely), and deleting System Restore points and Shadow volumes and stopping the ability to create them.
CVE-2021-36934 Windows Elevation of Privilege Vulnerability
This is known as the HiveNightmare Vulnerability.
Restrict access to the contents of %windir%\system32\config
1. Open Command Prompt or Windows PowerShell as an administrator.
2. Run this command:
icacls %windir%\system32\config\*.* /inheritance:e
Delete Volume Shadow Copy Service (VSS) shadow copies
1. Delete any System Restore points and Shadow volumes that existed prior to restricting access to %windir%\system32\config.
2. Create a new System Restore point (if desired).
Impact of workaround Deleting shadow copies could impact restore operations, including the ability to restore data with third-party backup applications.
Note You must restrict access and delete shadow copies to prevent exploitation of this vulnerability.
CVE-2021-34527 Windows Print Spooler Remote Code Execution Vulnerability
Determine if the Print Spooler service is running
Run the following in Windows PowerShell:
Get-Service -Name Spooler
If the Print Spooler is running or if the service is not set to disabled, select one of the following options to either disable the Print Spooler service, or to Disable inbound remote printing through Group Policy:
Option 1 – Disable the Print Spooler service
If disabling the Print Spooler service is appropriate for your enterprise, use the following PowerShell commands:
Stop-Service -Name Spooler -Force
Set-Service -Name Spooler -StartupType Disabled
Impact of workaround Disabling the Print Spooler service disables the ability to print both locally and remotely.
Option 2 – Disable inbound remote printing through Group Policy
You can also configure the settings via Group Policy as follows:
Computer Configuration / Administrative Templates / Printers
Disable the “Allow Print Spooler to accept client connections:” policy to block remote attacks.
You must restart the Print Spooler service for the group policy to take effect.
Impact of workaround This policy will block the remote attack vector by preventing inbound remote printing operations. The system will no longer function as a print server, but local printing to a directly attached device will still be possible.